Fluoro-alkyl-substituted polynitro aromatic amines and nitramines

ABSTRACT

1. THE COMPOUNDS HAVING THE FORMULA:   1-(R1-N(-R2)-),2,4,6-TRI(O2N-),3-R4,5-R3-BENZENE   WHERE R1 IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND A NITRO RADICAL; AND R2, R3 AND R4 ARE EACH SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, A MONOVALENT LOWER ALKYL RADICAL, AND A FLUORO-SUBSTITUTED MONOVALENT LOWER ALKYL RADICAL PROVIDED THAT AT LEAST ONE OF THE SUBSTITUENTS R2, R3 AND R4 IS FLUORO-SUBSTITUTED MONOVALENT LOWER ALKYL RADICAL.

United States Patent Office Patented Feb. 9, 1971 3,562,333FLUORO-ALKYL-SUBSTITUTED POLYNITRO AROMATIC AMINES AND NITRAMINES Josef.l. Schmidt-Collerus, Denver, (1010., and Don N. Gray, Towson, Md.,assignors to the United States of America as represented by theSecretary of the Air Force N Drawing. Filed Jan. 28, 1964, Ser. No.340,837

Int. Cl. C07c 87/60 U.S. Cl. 260-577 6 Claims This invention relates tofluoro-alkyl-substituted polynitro aromatic amines and nitramines. Morespecifically, this invention concerns itself with fiuoro-substitutedalkyl group derivatives of picramide (I) and tetryl (II) as representedby the following structural formulas:

IIQH2 OzNN CH I l 0 2 (I) N 0 2 (II) in which fluorine is substituted inthe N-alkyl group or on the benzene nucleus of the aromatic ring. Thepreferred compounds of this invention are the trifluoromethylsubstituted derivatives of picramide and tetryl.

Picramide, tetryl, ethyl tetryl and butyl tetryl are wellknown for theiruse in military munitions as primary explosives, boosters, anddetonators. These explosives exhibit a much higher explosive potentialthan TNT or picric acid; but are distinctly more sensitive to shock andheat. Consequently, their military utility is minimized because of thesevere conditions encountered by the military during field operations.With this invention, however, it has been found that the undesirablesensitivity characteristics of the above referred to explosives can beabrogated by providing a new class of fiuoro-alkyl-substitutedderivatives of picramide and tetryl. These new compounds, althoughexhibiting a high explosive potential are dis tinctly more resistant toshock and heat. As a result, they are much more useful when employed bythe military as primary explosives, detonators, boosters and in otherexplosive applications. Additionally, the compounds of this inventionare useful as dyestuffs in the coloration of cellulosic textilematerials and as intermediates in the production of other novel anduseful compounds.

Accordingly, the primary object of this invention is to provide a newclass of explosives Which are characterized by a high explosivepotential coupled with a high degree of thermal and shock resistivity.

Another object of this invention is to provide a new class offiuoro-substituted alkyl group derivatives of picramide and tetryl.

A further object of this invention is the preparation of novel dyestuffsand dyed textile materials.

The new compounds of this invention have the following structuralformula:

wherein R may be hydrogen or a nitro radical and R R and R may eachrepresent hydrogen, a monovalent lower alkyl radical having from 1 to 5carbon atoms, or a fluoro-substituted monovalent lower alkyl radicalhaving from 1 to 5 carbon atoms provided that at least one of thesubstituents R R and R is a fiuoro-alkyl group.

Illustrative of the lower alkyl and fiuoro-substituted lower alkylradicals represented by R R and R are the following: -CF CH CF CH CHFCH2CH2CH2CHF3, 'CH3, C2H5, -C3H8, 01' Othfir monovalent lower alkyl andfluorine-containing lower alkyl radicals either straight chained orbranched in structure.

The compounds of this invention represent a new class of explosives;namely, N-fluoro-alkyl and fluoro-alkylsubstituted picramides andnitramines. Typical compounds of the invention are conveniently preparedby nitrating an appropriate substituted trinitroaniline. This startingcompound is in turn prepared by effecting a reaction between anequimolar mixture of a fiuoro-substituted trinitrobenzene, such aspicryl fluoride; or a chlorosubstituted trinitrobenzotrifluoride, withammonia or an appropriate substituted amine. The synthesis schemesdisclosed by the following examples produce specific compounds but isalso representative of the method for synthesizing the whole genericgroup by the judicious choice of appropriately substituted startingmaterials.

The following examples illustrate the new compounds of this inventionand the basic synthesis scheme by which they are prepared. Theseexamples, however, are by way of illustration only and are not to beconsidered as limiting the scope of the invention in any way.

EXAMPLE 1 To a solution of 52.5 g. (0.17 mole) of 3-chloro-2,4,6-trinitrobenzotrifluoride in 250 ml. of benzene in a 1-liter separatoryfunnel was added a solution of 50 ml. of 40% monomethylamine in 150 ml.of distilled water. This mixture was shaken and kept cool by holding thefunnel under the water tap. After ten minutes shaking, the solution wasdark red. At this point a solution of 20 g. of sodium carbonate in 200ml. of water was added and again the mixture shaken. The benzene layerwas removed, and evaporated on a steam bath, leaving a bright-yellowsolid residue. Recrystallization from ethanol gave an 82% yield of 3trifiuoromethyl-2,4,6-trinitro-N-methylaniline; M.P. 137-138 C.

EXAMPLE 2 Five grams of 3-chloro-2,4,6-trinitrobenzotrifiuoride wasdissolved in 30 ml. of dry methyl alcohol and the solution cooled in anice bath. Gaseous ammonia was then bubbled through the solution until apermanent red color was present. The solution was then filtered througha hard filter and the alcohol solution was concentrated to onethird itsvolume under reduced pressure to give a dark red precipitate. This wasfiltered and the filter cake washed with a benzene-n-hexane (50:50)solution. This gave 3- trifluoromethyl picramide which decomposed at 195C. and changed from the red to the yellow isomorphic form.

EXAMPLE 3 The nitration of 3 trifluoromethyl-2,4,6-trinitro-N-methylaniline from Example 1 was accomplished :by dissolving 12.5 g.(0.04 mole) of the amine in ml. of concentrated sulfuric acid, coolingexternally with an ice bath, then slowly adding 15 ml. of concentratednitric acid with stirring. After the reaction solution had been allowedto stand for several hours at room temperature it waspoured over about500 g. of shaved ice and the precipitated white solid was collected on afilter and air dried. Recrystallized from 95% ethanol yielded 12 g.(84.5% yield) of 3-trifluoromethyl-2,4,6-trinitrophenylmethylnitramineas a white solid.

EXAMPLE 4 To a solution of 49.4 g. (0.2 mole) picryl fluoride in 400 ml.of 95% ethanol was added 33.5 g. (0.25 mole) of trifluoroethylaminehydrochloride. This suspension was heated to dissolve the solids, thencooled externally with an ice bath. At this point, 50 g. (0.5 mole) ofsolid sodium carbonate was added slowly with moderate stirring. Evidenceof the reaction was noted by a slight temperature rise, evolution of COand the presence of the characteristic amine odor. The deep-orangesolution was then heated on the steam bath for about one hour, pouredonto ice and acidified with 3 N hydrochloric acid to congo red. Thelight-yellow solid was collected on a filter, washed with cold water andair-dried. Recrystallized from 95% ethanol yielded 38.8 g. (62.5% yield)of N-beta,beta,betatrifluoroethyl 2,4,6 trinitroaniline as a yellowsolid; M.P.=6770 C. Further recrystallization from 95% ethanol yielded28.7 g. of pale-yellow crystals; M.P.= 73.574.0 C.

Analysis.-Calculated for C H N O F (percent): C, 30.98; H, 1.62; N,18.06; F, 18.4. The actual values found were (percent): C, 31.24; H,1.74; N, 18.21; F, 18.3.

EXAMPLE 5 The nitration of N-beta,beta,beta-trifluoroethyl-2,4,6-trinitroaniline of Example 4 was accomplished by dissolving 12.5 g.(0.035 mole) of the amine in 250 ml. of concentrated sulfuric acid,cooling externally with an ice bath, then slowly adding 14 ml. ofconcentrated (90%) nitric acid with stirring, keeping the temperaturebelow C. during the addition. After the reaction solution had beenallowed to stand for several hours at room temperature, it was pouredover about 1 kg. of shaved ice. The precipitated white solid wascollected on a filter and air-dried. Recrystallized from 95% ethanolyielded 12.1 g. (98% yield) of2,4,6-trinitrophenyl-beta,beta,beta-trifluoroethylnitramine as a whitesolid; M.P. 116118 C.

Analysis.Calculated for C H N O F (percent): C, 27.05; H, 1.14; N,19.72; F, 16.1. Molecular weight (Rast Camphor), 301.18. The actualvalues found were (percent): C, 27.46; H, 1.29; N, 19.92; F, 16.3.Molecular weight, 295.

Tetryl, when dissolved in sulfuric acid, is connected to methylpicramide (2,4,6-trinitro-monomethyl-aniline) and nitric acid. This factis utilized to determine the presence of the nitramine linkage (NNO inorganic materials. The nitric acid produced in the reaction oxidizesdiphenylamine (colorless) to a quinoidimonium sulfate ofN,N'-diphenylbenzidene (blue). It was found that both tetryl and ethyltetryl (2,4,6-trinitrophenylethylnitramine) react at once at roomtemperature; however, trifluoroethyl tetryl gives a color reactionslowly at steam bath temperatures. This decreased lability of theN-nitro linkage is attributed to the inductive effect of the fluorinesubstitution on the ethyl group.

The following two tables disclose the thermal and impact sensitivity ofprior known explosives and compares them with the compounds of thisinvention. The information set forth in Table I may be found in theEncyclopedia of Chemical Technology, edited by R. E. Kirk and D. F.Othmer, vol. 6, pp. 54 and 1551, 'Interscience Encyclopedia, Inc. NewYork, N.Y. The impact sensitivity data of Table II was ascertained bythe Naval Ordinance Laboratory and may be found in Navord Report 5335,Impact Sensitivities, (Oct. 18, 1956), by W. P. Besser and P. G.Rivette.

TABLE I Thermal sensitivity Explosive: Explosion temperature, C. Tetryl257 RDX 260 PETN 225 Nitroglycerin 222 Picric acid 322 It has been foundthat the explosion temperature of 2,4,6 trinitrophenyl beta,beta,betatrifiuoroethylnitramine, the reaction product from Example 5, is between340 C. and 360 C. and, hence, is more stable to heat than those priorknown explosives set forth in Table I.

The explosion temperature of ethyl tetry-l is between 260 5 C. and 280C. The explosion temperature of Table I is defined as that temperaturein degrees centigrade required to cause an explosion in 5 seconds.

TABLE II Impact sensitivity Explosive: Impact height, cm. Tetryl 2742RDX 25 PETN 12-1 3 15 Nitro glycerin 4-6 Picric acid 73-93 TNT l 5 8-l71 Ethyl tetryl 1 81 TP ethyl tetryl 2 1 5 6 12,4,G-trinitrophenyletllylnitramine.

2 2,4,S-trinitrophenyl-beta,beta,beta-trifiuoroethylnitramine.

From an examination of the information presented in Table II, it can beseen that 2,4,6-trinitrophenyl-beta,beta, beta-trifluoroethylnitramine,the reaction product from Example 5, is less impact sensitive, with theexception of TNT, than the prior known explosives referred to in TableII. The impact height of Table II is defined as that height incentimeters for 50% fire using an ERL machine with a type 12 toolkilograms weight).

An explosive compound is considered to be stable if less than 2 cc. ofgas, corrected to normal temperature and pressure, are evolved per gramper 48 hours at 100 C. Stability tests show that2,4,6-trinitrophenyl-beta,beta,betatrifiuoroethylnitramine evolves lessthan 2 cc. of gas at 100 C. for 48 hours and, hence, is placed insatisfactory stability Class I. All military explosives, such asammonium picrate, PETN, RDX, tetryl and TNT, must meet this criterion.The power of 2,4,6-trinitrophenyl-beta,beta,beta-trifluoroethylnitramine is 125% that of TNT as measured by thetrauzl lead block test.

From a consideration of the foregoing, it can be seen that the presentinvention provides a new class of explosive compounds which areespecially useful when employed as explosives in military munitions.These compounds exhibit a high explosive potential together with aminimum susceptibility to shock and heat.

The reaction products of Examples 1, 2 and 4 are representative of a newclass of compounds; namely, fluoroalkyl and N-fiuoro-alkyl-substitutedpicramides. This class of compounds, in addition to being useful asexplosives, dyes natural and synthetic fibers yellow and their ammoniumsalts dye those fibers red. Representative of the N-fiuoro-alkyl andfluoro-alkyl-substituted nitramines are the reaction products ofExamples 3 and 5.

Obviously many modifications and variations of this invention may bemade without departing from the spirit and scope thereof and only suchlimitations should be imposed as fall within the scope of the appendedclaims.

What is claimed is:

1. The compounds having the formula:

R II I-Rz O N- N02 where R is selected from the group consisting ofhydrogen and a nitro radical; and R R and R are each selected from thegroup consisting of hydrogen, a monovalent lower alkyl radical, and afluoro-substituted monovalent lower alkyl radical provided that at leastone of the sub- 6 stituents R2, R3 and R4 is fluoro-substitutedmonovalent References Cited lower alkyl radical UNITED STATES PATENTS4'11 11 1-2 4,6-t' '1 -N- 1111 '1' 2 3 n Home me yamme 3,418,372 12/1968Taylor 149 105X 3. 3-tr ifluorqrn e thyl pi cramidemiiefa-tnfluoromethyl 2,4,6 tnmtrophenylmethyl-mtra- 5 LELAND A.SEBASTIAN Primary Examiner 5. N-beta b ta,beta-trifluoroethyl-2,4,6trinitroanilir e. Us CL X Rmig.2,4,6-tr1n1tr0phenyl-beta,beta,beta-tnfluoroethylnltra- 149 105; 26O578

1. THE COMPOUNDS HAVING THE FORMULA: